Unfortunately as your MEP has expired the new regs (came in 16 March) require you to renew your MEP as well - which would realistically mean doing the test in the aircraft (both MEP and IR). If you have sufficient time available on the SP ME IR you could renew the MEP as a separate flight and then do the IR in the sim but would be probably a lot more expensive, the bit below is from CAP 1879. If your SEP is not current then only your MEP IR will be revalidated.
References: Subpart G, FCL.625, FCL.625(A), FCL.625(H)) There has been a change to FCL.625, Instrument Rating-Validity, revalidation and renewal for aeroplanes and helicopters, which applies to national and Part-FCL licence holders. When revalidating or renewing an IR(A) or IR(H), the licence holder must hold the relevant valid class or type rating, unless revalidating or renewing the privileges of the class or type rating at the same time as renewing the IR. Examiners need to ensure that the applicant meets these requirements when conducting Proficiency Checks and sign the Certificate of Revalidation accordingly. Pilots who have an IR with SE and ME privileges on their licence need to hold current single engine and multi engine rating when revalidating or renewing their IR if they wish to fly IR in single engine and multi engine aeroplanes. Pilots only valid in a multi engine class rating at the time the IR is revalidated/renewed can only be endorsed with an IR valid for multi engine aeroplanes (IR SP ME). The legislation states that the applicant must “hold the relevant class or type rating unless the IR revalidation is combined with the renewal of the relevant class or type rating”.
IR.SE.ME class/SE holders: Should an IR proficiency check be completed in a multi- engine whilst the candidate only holds a valid single engine rating, the candidate will have to renew the multi engine and retake the IR proficiency check in order to regain IR multi engine privileges. For example, a revalidation or renewal of an IR by Proficiency Check completed in a ME class of aeroplane or qualified FNPT II on 15th March 2020. The pilot under check only holds a valid SEP Class Rating, no valid multi engine rating is held, the Examiner is only able to endorse IR SP SE on the Certificate of Revalidation in the pilot’s licence. The current practise is where the IR SP ME automatically confers IR SP SE privileges. This practice ends as of 16 March 2020.